This invention generally relates to the art of protecting articles that have metallic surfaces which are susceptible to abrasion damage or corrosion and has particular reference to protecting gold-plated articles of jewelry and wristwatch components (such as bracelets and cases) with a transparent coating of one or more selected inert materials. The invention also provides methods for coating such articles with one or more overlying protective films that are transparent and composed of abrasion-resistant material.
As is well known, many articles of merchandise have metallic surfaces which inherently become dull or tarnished in the environment in which the article is used. For example, hardware items such as building-identification plaques, handrails, doorknobs, decorative doorknockers, etc. that are composed of brass or a similar metal oxidize quite rapidly and require constant polishing and waxing to maintain a brilliant pleasing appearance. This is also an age old problem with articles such as flatware, trays, trophies, etc. that are made of silver or are silver plated.
While articles such as fine jewelry and the like that are made from solid gold or have gold-plated surfaces do not tarnish and thus do not present such a maintenance problem, they scratch easily and soon become unsightly when subjected to the constant abrasion and "rubbing action" encountered during normal everyday use. Since gold is relatively soft material, it also wears away quite rapidly when subjected to such conditions. If the article is gold-plated, this frequently exposes the base metal and creates an unsightly corroded appearance in the case of articles (such as chains, rings, lockets, watchbands, etc.) that are in direct contact with the person's body. These characteristics thus present serious problems in the production and marketing of such items as gold-plated jewelry and gold-plated bracelets and cases for wristwatches. In order to compensate for the loss of gold that occurs during use by the customer, relatively thick gold plating is customarily used on high quality merchandise of this type to ensure that the article will retain its original pleasing appearance. However, in view of the extremely high cost of gold and the likelihood that it will become even more expensive in the future, the use of such heavy gold plating presents a serious economic problem in the watch and jewelry industries.
A practical and reliable means for protecting gold and gold plated articles such as wristwatch components and the like from rapid wear and unsightly scratching (as well as corrosion if the gold plating has worn through) without materially changing its "natural" finish or appearance would, accordingly, not only be very desirable from a quality and marketing standpoint but would be very advantageous from a production and cost reduction standpoint. Such protective means would also be very useful in preventing skin reactions and similar problems that are sometimes encountered by certain individuals when they wear a ring, chain or similar article that is made from a particular metal or alloy.